Problem with setting formfieldfont

Hi,
we have a problem find the right way to set the font of a formfield.
Below the code we did try:

  PDF := TDebenuPDFLibrary.Create;
  UnlockResult := PDF.UnlockKey(cDebenuLicenseKey);
  try
    if (UnlockResult = 1) then begin

      // Load Template
      PDF.LoadFromFile(ATemplate, '');

      // Set the paper size
      PDF.SetPageSize('A4');

      // Set the origin to the top-left corner
      PDF.SetOrigin(1);

      // Set the measurement units to millimetres
      PDF.SetMeasurementUnits(1);


      FontID := PDF.AddTrueTypeFont('Arial', 0);
      FieldIndex := APDF.NewFormField('LvBez', 1);

      PDF.SetFormFieldBounds(FieldIndex, ALeft, ATop, AWidth, AHeight);
      PDF.SetFormFieldPage(FieldIndex, APageNumber);

      PDF.SetFormFieldFont(FieldIndex, FontID);

      FontID := PDF.AddTrueTypeFont('Courier New', 0);
      FieldIndex := APDF.NewFormField('LvNr', 1);

      PDF.SetFormFieldBounds(FieldIndex, ALeft, ATop, AWidth, AHeight);
      PDF.SetFormFieldPage(FieldIndex, APageNumber);

      PDF.SetFormFieldFont(FieldIndex, FontID);

      // Compress the contents of the file
      PDF.CompressContent;

      // Save File
      PDF.SaveToFile(AFileName); 
    end;

  finally
    PDF.Free;
  end;

The second field should have font "Courier New" but it doesn't.

Could anybody help us to understand better how to do this.

Regards,
Josef